|Number|Serial No|Entered Service|Withdrawn|Kilometres Travelled|
|---|---|---|---|---|
|4101|1000|1 Dec 1953|6 Jun 1973|463,514|
|4102|1002|30 Oct 1953|30 Jun 1975|492,650|
|4103|1003|18 Jan 1954|2 Apr 1974|462,871|
|4104|1004|13 Jan 1954|12 Oct 1973|440,810|
|4105|1005|8 Feb 1954|?|?|
|4106|1006|21 Jan 1954|4 Aug 1972|406,288|
|4107|1007|25 Jan 1954|11 Aug 1973|446,167|
|4108|1008|22 Feb 1954|20 Dec 1967|402,026|
|4109|1009|11 Mar 1954|9 Feb 1972|426,074|
|4110|1010|10 Feb 1955|20 May 1974|476,489|

Question: which locomotive entered service first: 4107 or 4103?
Answer: 4103